Remote controls are commonly used for controlling various consumer electronic devices, such as televisions and stereo systems, from a distance. As an example, the ubiquitous television remote control comprises a wireless handheld device with buttons for adjusting various television settings such as the television channel and volume. The typical procedure for controlling a consumer electronic device using a remote control is to point the remote control in the direction of the consumer electronic device and then to wirelessly transmit various device commands to the consumer electronic device via the selection of various buttons on the remote control.
Most remote controls transmit infrared (IR) signals or radio-frequency (RF) signals in order to control the remote consumer electronic devices. Many different infrared transmission protocols exist. One infrared transmission protocol is the NEC IR transmission protocol, which uses pulse distance encoding of the message bits. Another infrared transmission protocol is the RC-5 protocol, which provides a one-way protocol for transmitting device commands to a consumer electronic device. In the case of the RC-5 protocol, the remote control typically includes a transmitter IC driving an IR emitter source (e.g., an IR LED) for generating an IR signal. The remote control transmits the IR signal including the device commands via a Manchester coded bitstream modulating a 36-40 kHz carrier signal. The transmitted IR signal is then detected by an IR enabled consumer electronic device using an IR light sensor (e.g., a photodiode or phototransistor) and demodulated such that the consumer electronic device can act in accordance with the received device commands.
Universal remote controls have been developed to consolidate a large number of different remote controls, due to different IR transmission protocols used by various consumer electronic device manufacturers and the fact that each consumer electronic device is typically shipped with its own remote control, into a single universal remote control. A universal remote control may be programmed to control many different consumer electronic devices utilizing different IR transmission protocols. For example, a single universal remote control may be configured to control a television, a VCR, a DVD player, and a stereo system.